Overview
ISO 8262-1:2005 (IDF 124-1:2005) is the reference gravimetric method for determining fat content in milk-based and other infant foods where the Röse‑Gottlieb method is not suitable. It specifies the Weibull‑Berntrop (WB) gravimetric principle-acid digestion, filtration and solvent extraction-adapted for infant foods that contain high levels of starch/dextrin (>5% dry matter) or other ingredients (vegetables, fruit, meat), significant free fatty acids, or hard lumps.
Key topics and technical requirements
- Scope and applicability: Designed for infant foods to which the Röse‑Gottlieb method is not applicable (e.g., >5% starch/dextrin). Also suitable when free fatty acids or undissolved lumps occur.
- Analytical principle: Boil a test portion with dilute HCl, filter the hot digest on wetted filter paper, dry the residue and extract fat with n‑hexane or light petroleum; remove solvent and weigh the extracted fat.
- Reagents & materials: Analytical‑grade reagents; dilute HCl (~20% mass fraction) prepared by mixing specified volumes of concentrated acid and water; solvent free from water; pleated filter paper (150 mm), defatted cotton wool, optional diatomaceous earth or lactose for difficult samples.
- Apparatus examples: Soxhlet‑type extraction or continuous/semi‑continuous extractor, 150 ml flat‑bottom extraction flasks, analytical balance, blenders for homogenization, drying oven (102 °C ± 2 °C), distillation apparatus for solvent removal.
- Quality checks: Blank tests for solvent and filter paper (residue limits specified), solvent boiling range (30–60 °C) and solvent residue requirement (≤1.0 mg in test), and filter paper residue (≤2.5 mg).
- Safety: Procedure involves volatile, flammable solvents; laboratories must observe appropriate electrical and handling safety measures.
Practical applications and users
- Who uses it: Food testing laboratories, infant formula and baby‑food manufacturers, dairy quality control, regulatory agencies and conformity assessment bodies.
- Why use it: Provides a reference, harmonized method to obtain accurate fat content when carbohydrate or non‑milk ingredients interfere with standard Röse‑Gottlieb extraction. Useful for product labelling, regulatory compliance, quality assurance and interlaboratory comparisons.
Related standards
- ISO 8262 series (Parts 2 and 3 cover edible ices and special cases)
- ISO 8381 (Röse‑Gottlieb method for other milk‑based products)
- ISO 707 (recommended sampling of milk and milk products)
Keywords: ISO 8262-1:2005, Weibull‑Berntrop, fat determination, gravimetric method, infant foods, Röse‑Gottlieb, milk products, reference method.
Open preview (PDF)Milk products and milk-based foods — Determination of fat content by the Weibull-Berntrop gravimetric method (Reference method) — Part 1: Infant foods